1. Field of the Invention
The invention relates to a one-piece, multi-shank contact spring for miniature plug connectors, particularly for high-frequency signals.
2. The Prior Art
A one-piece, multi-shank contact spring for miniature plug connectors is described in DE 43 30 390 C2. The contact spring, which is continuously punched from a metal strip and bent, carries two spring shanks, the free ends of which form two contact cones that lie opposite one another, as well as a contact intake for a contact blade. The contact intake is offset laterally and rotated by 90° relative to the planar spring shanks, and for this reason, even extremely long contact blades can be used. The contact blade is pushed in between the intake cones and the contact cones as the connection is made, all the way to a stop. This method of construction is particularly well suited for multi-point plugs having small raster intervals.
A one-piece contact spring having two spring shanks that lie opposite one another, for the press-in technique, is described in German Patent No. DE 33 24 737 C2.
There are also one-piece contact springs that form a more or less closed cage for a contact blade or contact pin (German Patent No. DE 38 17 803 C3, European Patent No. EP 0 390 865 B1, European Patent No. EP 0 958 638 B1, U.S. Pat. No. 5,281,175). However, the latter terminals are not completely in line with the current trend in the industry, that of increasing the density of the electrical signal connections and thereby saving space and costs.
All of the contact springs indicated above have the disadvantage that the contact-forming region between the contact spring and a plug-in lead, including, for example, flat contact blades, square or round contact pins, and circuit board leads, is directed at a point-shaped or line-shaped zone of contact points that lie opposite one another, and this does not meet any needs for for a higher current carrying capacity and, in particular, for high-frequency applications of a plug connector. This is because for high-frequency signals, aside from a reliable mechanical and electrical connection, an impedance adaptation, and reciprocal shielding of the contact springs of a plug relative to one another, it would be desirable to also reduce or completely avoid the negative effects of reflections on the electrical transmission behavior of a plug connector. These effects are caused by the fact that a signal component runs beyond the contact zone all the way to the tip of a plug-in lead, and is reflected there. In this way, the input signals are split up starting from the plug connector, and a running time difference that is dependent on the free length of the plug-in lead is imposed on part of the signals, which difference can result in such signal impairments as echo and signal weakening in the further transmission path. On the other hand, however, the insertion length of a plug-in lead into a contact spring cannot simply be reduced as desired, because in this way, reliable contacting and parallel intake of the plug-in lead into a contact spring, which also has an insertion and guide function for the plug-in lead, would suffer. This is particularly true for multi-pole electrical miniature plug connectors, as they are used, for example, in communications technology and computer technology. If, on the other hand, the contacting of plug connectors were to be placed at the end of the plug-in leads, the contact reliability is no longer guaranteed, due to unavoidable tolerances, since the contact spring would only be allowed to just touch the tip of the plug-in lead, in order to prevent reflections.